JP4314532B2 - Near infrared absorption film - Google Patents

Description

  The present invention relates to an optical film that absorbs near-infrared rays, and in particular, relates to a near-infrared absorbing film that has little change in color tone at high temperatures and is excellent in durability.

Optical films having near infrared absorption ability have the property of blocking near infrared rays and allowing visible light to pass through, and are used in various applications.
In recent years, plasma displays have attracted attention as thin large-screen displays. However, there is a problem that electronic devices using a near-infrared remote controller may malfunction due to near infrared rays emitted from the plasma display. A film having infrared absorbing ability is used.

The film having the ability to absorb near infrared rays includes: (1) a phosphoric acid glass containing metal ions such as copper and iron; (2) a layer having different refractive indexes is laminated to interfere with transmitted light; An interference filter that transmits wavelengths, (3) an acrylic resin film containing copper ions in a copolymer, and (4) a film in which a layer in which a pigment is dispersed or dissolved in a resin are laminated.
Among these, the film (4) has good workability and productivity, has a relatively large degree of freedom in optical design, and various methods have been proposed (see Patent Documents 1 to 9).
JP 2002-82219 A JP 2002-138203 A JP 2002-214427 A JP 2002-264278 A JP 2002-303720 A JP 2002-333517 A JP 2003-82302 A Japanese Patent Laid-Open No. 2003-96040 JP 2003-114323 A

Some of these methods have the ability to sufficiently block near-infrared rays emitted from a plasma display and have little change with time even when used for a long time.
On the other hand, in order to reduce the weight of the display and improve the image quality, a method has been proposed in which an optical filter including a near-infrared absorbing film is bonded to a plasma display panel without using glass. In this method, the near-infrared absorbing film can easily transmit the heat of the display, and there is a problem that the near-infrared absorbing film is easily deformed due to the absence of glass, and the near-infrared absorption has excellent heat resistance and flexibility. A film is desired.

  The object of the present invention was made to solve the above-mentioned problems of the prior art, and is a near-infrared absorbing film that absorbs a large and wide range of the near-infrared region, and has high durability, particularly heat resistance. It is providing the near-infrared absorption film which is excellent in a softness | flexibility and is excellent in a softness | flexibility.

  The near-infrared absorbing film of the present invention that has solved the above-mentioned problems has the following configuration.

1st invention is a near-infrared absorption film which provided the near-infrared absorption layer which consists of a composition mainly comprised from a near-infrared absorption pigment | dye and resin on a transparent base material, Comprising: It is ion in the said composition. It is a near-infrared absorption film characterized by containing 0.1 mass% or more and 10.0 mass% or less of a liquid.

  A second invention is the near-infrared absorbing film according to the first invention, wherein the near-infrared absorbing dye contains a diimmonium salt compound.

  A third invention is the near-infrared absorbing film according to the second invention, wherein the diimmonium salt compound is a diimmonium salt compound having bis (trifluoromethanesulfonyl) imidic acid as a counter ion.

A fourth invention is the near-infrared absorbing film according to any one of the first to third inventions, wherein the ionic liquid contains bis (trifluoromethanesulfonyl) imidic acid as an anion.

5th invention is a near-infrared absorption film in any one of the 1st- 4th invention characterized by the resin which comprises a near-infrared absorption layer being an acrylic resin.

  When the near-infrared absorbing film of the present invention is installed on the front surface of the plasma display as a near-infrared absorbing filter, like the conventional near-infrared absorbing filter, it absorbs unnecessary near-infrared rays emitted from the display and malfunctions of precision equipment. In addition to being able to prevent color change due to heat, the color change due to heat can be greatly reduced, which contributes to higher image quality of plasma displays and increases the degree of freedom in designing optical filters. .

Hereinafter, the present invention will be described in detail.
(Transparent substrate)
In the present invention, the transparent substrate is not particularly limited, but preferably has a total light transmittance of 80% or more and a haze of 5% or less. When the substrate is inferior in transparency, not only the brightness of the display is lowered, but the sharpness of the image becomes poor.

  Examples of such transparent base materials include polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate, phenol-based, and urethane-based plastic films. Or what stuck together a sheet | seat, glass, and these arbitrary 2 types or more is mentioned. A polyester film having a good balance between heat resistance and flexibility is preferable, and a polyethylene terephthalate film is more preferable.

  Polyester film suitable as a transparent substrate for use in the present invention, as dicarboxylic acid component, aromatic dicarboxylic acid or ester thereof such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and glycol component, ethylene glycol, diethylene glycol, Polyester chips obtained by esterification or transesterification of 1,4-butanediol, neopentyl glycol, etc., and then polycondensation reaction are dried, melted with an extruder, and extruded from a T die into a sheet. The film is produced by stretching the obtained unstretched sheet in at least one axial direction, and then performing heat setting treatment and relaxation treatment.

  The film is particularly preferably a biaxially stretched film from the viewpoint of strength and the like. Examples of the stretching method include a tubular stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and the like, but a sequential biaxial stretching method is preferable in view of flatness, dimensional stability, thickness unevenness, and the like. The sequential biaxially stretched film is, for example, roll-stretched in the longitudinal direction at a glass transition temperature (Tg) to (Tg + 30 ° C.) of 2.0 to 5.0 times in the longitudinal direction and then preheated with a tenter 120 Stretch in the width direction 1.2 to 5.0 times at ~ 150 ° C. Furthermore, after biaxial stretching, it can be produced by performing heat setting treatment at a temperature of 220 ° C. or higher (melting point−10 ° C.) and then relaxing by 3 to 8% in the width direction. Further, in order to further improve the dimensional stability in the longitudinal direction of the film, a longitudinal relaxation treatment may be used in combination.

  In order to provide the film with handleability (for example, rollability after lamination), it is preferable to incorporate particles and form protrusions on the film surface. As particles to be included in the film, inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, alumina, etc., heat resistant polymer particles such as acrylic, PMMA, nylon, polystyrene, polyester, benzoguanamine / formalin condensate, etc. Is mentioned. From the viewpoint of transparency, the content of particles in the film is preferably small, for example, preferably 1 ppm or more and 1000 ppm or less. Furthermore, it is preferable to select particles having a refractive index close to that of the resin used from the viewpoint of transparency. Moreover, in order to provide various functions as needed, the film may contain a light-resistant agent (ultraviolet ray inhibitor), a pigment, an antistatic agent, and the like.

  In the present invention, when an antireflection layer is provided on the surface opposite to the surface on which the near-infrared absorbing layer is laminated, the near-infrared absorbing dye due to ultraviolet rays incident from the outside is liable to deteriorate, so an ultraviolet absorber is contained in the transparent substrate. It is preferable to make it.

UV absorbers are broadly classified into organic UV absorbers and inorganic UV absorbers. From the viewpoint of ensuring transparency, it is desirable to use organic UV absorbers (low molecular type and high molecular type). . Although it does not specifically limit as an organic type ultraviolet absorber (low molecular type), For example, a benzotriazole type, a benzophenone type, a cyclic imino ester type, etc., and these combination are mentioned. Among these, from the viewpoint of durability, benzotriazole type and cyclic imino ester type are preferable, and it is desirable to use an ultraviolet absorber having a decomposition temperature of 290 ° C. or higher in order to withstand the temperature at the time of manufacturing the substrate.

  The content of the ultraviolet absorber is preferably adjusted so that the transmittance at a wavelength of 380 nm or less is 10% or less so that the photodegradation of the near-infrared absorbing layer can be suppressed. Specifically, the content of the ultraviolet absorber is preferably 0.1 to 4% by mass in the transparent substrate, and more preferably 0.3 to 2% by mass. If the amount of the ultraviolet absorber is too small, the ultraviolet absorbing ability is decreased, and if it is too large, the film may be yellowed or the film-forming property of the film may be deteriorated.

  The transparent substrate used in the present invention may be a single layer film or a composite film of two or more layers in which a surface layer and a center layer are laminated. In the case of a composite film, there is an advantage that the functions of the surface layer and the center layer can be designed independently. For example, by containing particles only on the thin surface layer and forming irregularities on the surface, the handling property is maintained, but the thick central layer does not substantially contain particles, so that the composite film as a whole is transparent. Can be further improved. In addition, in the case of imparting ultraviolet absorbing ability, by containing an ultraviolet absorber only in the center layer, it is possible to reduce the precipitation of the ultraviolet absorber on the film surface during film production or over time, so near infrared absorption Adverse effects such as deterioration of heat resistance to the layer can be suppressed. The method for producing the composite film is not particularly limited, but considering productivity, after extruding the raw material of the surface layer and the central layer from separate extruders, leading to one die and obtaining an unstretched sheet, Lamination by the so-called coextrusion method that is oriented in at least one axial direction is particularly preferable.

  The thickness of the transparent substrate varies depending on the material, but when a polyester film is used, the lower limit is preferably 35 μm or more, more preferably 50 μm or more. On the other hand, the upper limit of the thickness is preferably 260 μm or less, more preferably 200 μm or less. When the thickness is small, not only the handling property becomes poor, but also when the film is heated at the time of drying so as to reduce the residual solvent of the near infrared absorption layer, the film tends to be wrinkled and flatness tends to be poor. On the other hand, when the thickness is large, not only is there a problem in terms of cost, but flatness due to curling tends to occur when the material is wound and stored in a roll shape.

(Middle layer)
The near-infrared absorbing filter of the present invention has a configuration in which a near-infrared absorbing layer is laminated on a transparent substrate, but for the purpose of improving the adhesion between the transparent substrate and the near-infrared absorbing layer and improving the transparency of the transparent substrate. It is preferable to provide an intermediate layer. In addition, when not containing particle | grains in a film, high transparency can be obtained, maintaining handling property by providing the intermediate | middle layer containing particle | grains simultaneously at the time of film manufacture.

  Examples of the resin constituting the intermediate layer include polyester resins, polyurethane resins, polyester urethane resins, acrylic resins, melamine resins, etc., so that the adhesion between the base material and the near infrared absorption layer is good. It is important to select, and specifically, if the resin constituting the substrate and the near-infrared absorbing layer is acrylic, it is preferable to select acrylic, copolymer polyester, or polyester urethane.

  The intermediate layer may contain a crosslinking agent for the purpose of improving adhesion and improving water resistance to form a crosslinked structure. Examples of the crosslinking agent include urea, epoxy, melamine, and isocyanate. In particular, when the resin is whitened under high temperature and high humidity and the strength is lowered, the effect of the crosslinking agent is remarkable. In addition, you may use the graft copolymer resin which has self-crosslinking property as resin, without using a crosslinking agent.

  The intermediate layer may contain various kinds of particles for the purpose of forming irregularities on the surface and improving slipperiness. Examples of the particles to be included in the intermediate layer include inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, and alumina, organic materials such as acrylic, PMMA, nylon, styrene, polyester, and benzoguanamine / formalin condensate. Particles. In addition, it is preferable to select particles having a refractive index close to that of the resin used from the viewpoint of transparency.

  Furthermore, in order to give various functions to the intermediate layer, a surfactant, an antistatic agent, a dye, an ultraviolet absorber, or the like may be contained.

  The intermediate layer may be a single layer if it has the desired function, but may be laminated in two or more layers as necessary.

  The thickness of the intermediate layer is not particularly limited as long as it has a desired function, but is preferably 0.01 μm or more and 5 μm or less. When the thickness is small, the function as an intermediate layer is hardly exhibited. On the contrary, when the thickness is thick, the transparency tends to be poor.

  As a method for providing the intermediate layer, a coating method is preferable. As the coating method, using a known coating method such as gravure coating method, kiss coating method, dip method, spray coating method, curtain coating method, air knife coating method, blade coating method, reverse roll coating method, etc. It can be provided by an in-line coating method in which a coating layer is provided, or an offline coating method in which a coating layer is provided after film production. Among these methods, the in-line coating method is not only excellent in cost, but it is not necessary to include particles in the transparent base material by including particles in the coating layer, so that the transparency can be improved to a high degree. This is preferable because it is possible.

(Near-infrared absorbing layer)
The near-infrared absorbing filter of the present invention is provided with a near-infrared absorbing layer made of a composition mainly containing a near-infrared absorbing dye and a resin directly or via an intermediate layer on a transparent substrate. The above-mentioned “mainly containing near-infrared absorbing dye and resin” means that the composition contains 80% by mass or more of near-infrared absorbing dye and resin.

  The near-infrared absorbing dye is a dye having a maximum absorption in the near-infrared region with a wavelength of 800 to 1200 nm, and is a diimmonium-based, phthalocyanine-based, dithiol metal complex-based, naphthalocyanine-based, azo-based, polymethine-based, anthraquinone-based , Naphthoquinone, pyrylium, thiopyrylium, squarylium, croconium, tetradehycholine, triphenylmethane, cyanine, azo, and aminium compounds. These compounds are used alone or in admixture of two or more, and are represented by the following formula (1), which has a large absorption in the near infrared region, a wide absorption region, and a high transmittance in the visible light region. It is preferable to contain a diimmonium salt compound.

  Specific examples of R1 to R8 in the above formula (1) include (a) methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, and ter-butyl group. , N-amyl group, n-hexyl group, n-octyl group, 2-hydroxyethyl group, 2-cyanoethyl group, 3-hydroxypropyl group, 3-cyanopropyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group Alkyl groups such as (b) phenyl groups, fluorophenyl groups, chlorophenyl groups, tolyl groups, diethylaminophenyl, naphthyl groups and other aryl groups, (c) vinyl groups, propenyl groups, butenyl groups, pentenyl groups and other alkenyl groups, (D) an benzyl group, a p-fluorobenzyl group, a p-chlorophenyl group, a phenylpropyl group, a naphthylethyl group, etc. Alkyl group, and the like.

  R9-12 may be hydrogen, fluorine, chlorine, bromine, diethylamino group, dimethylamino group, cyano group, nitro group, methyl group, ethyl group, propyl group, trifluoromethyl group, methoxy group, ethoxy group, propoxy Groups and the like.

X ⁻ represents fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, hexafluoroantimonate ion, hexafluorophosphate ion, tetrafluoroborate ion, bis (trifluoromethanesulfonyl) imidic acid. And ions. Among these, a diimmonium salt compound having a bis (trifluoromethanesulfonyl) imido ion as a counter ion is preferable from the viewpoint of an effect of improving heat resistance by containing an ionic liquid. This diimmonium salt compound is available as a commercial product. For example, Kayasorb IRG-022, IRG-023, IRG-024, IRG-068, Nippon Carlit Co., Ltd. CIR-1080, CIR-1081, CIR -1083, CIR-1085, CIR-1085F, CIR-RL and the like are preferable.

  In addition to the diimonium salt compound represented by the above formula (1), the near-infrared absorbing film of the present invention includes other near-infrared absorbing dyes for the purpose of expanding the absorption range of the near-infrared region and adjusting the color. You can also.

  Other near-infrared absorbing dyes that can be used in combination with the diimmonium salt compounds include phthalocyanine compounds, dithiol metal complex compounds, cyanine compounds, naphthalocyanine compounds, squarylium salt compounds, pyrylium salt compounds, thioperyllium compounds. Compounds, croconium compounds, indoaniline chelate dyes, indonaphthol chelate dyes, azo dyes, azo chelate dyes, aminium salt dyes, quinone dyes, anthraquinone dyes, polymethine dyes, triphenylmethane dyes, etc. Can be mentioned. Of these, phthalocyanine compounds and dithiol metal complex compounds, which are less likely to deteriorate under high temperature and high humidity, are preferable. When dyes that tend to deteriorate are used, not only does the stability of transmittance in the near-infrared region deteriorate with time, but the diimmonium salt compound acts as a quencher and deteriorates, and the near-infrared absorbing film becomes yellow. Discolor.

  Some of these are available as commercial products, such as phthalocyanine dyes manufactured by Nippon Shokubai (IR-1, R-2, IR-3, IR-4, IR-10, IR-10A, IR-12). , IR-14), cyanine dyes (TZ-111, 114, 119, 121, 123) manufactured by Asahi Denka, nickel complex dyes (MIR-101, MIR-111, MIR-121, MIR-) manufactured by Midori Chemical. 102, MIR-1011, MIR-1021), a cyanine dye (IR-301) manufactured by Yamada Chemical, a cyanine dye (YKR-2900) manufactured by Yamamoto Kasei, and a phthalocyanine dye (YKR-3070, YKR-3081). Can be mentioned.

In the present invention, in order to control the target absorption in the near-infrared region and the transmittance in the visible light region, the amount of the near-infrared-absorbing dye is 0.01 g / in any surface in the thickness direction of the near-infrared absorbing layer. it is preferable to adjust such that there and m ² to 1.0 g / m ² or less. When the amount of the near-infrared absorbing dye is small, the absorption ability in the near-infrared region is insufficient, and conversely, when it is large, the transparency in the visible light region is insufficient and the brightness of the display is lowered. .

  In the present invention, the method of laminating the near infrared absorbing layer on the transparent substrate includes a method of melting the near infrared absorbing dye and the resin by heating and providing them on the transparent substrate, and using the near infrared absorbing dye and the resin in an organic solvent. Examples of the coating method include dissolving, coating on a transparent substrate, drying, and laminating. A coating method in which uniformity in the width direction and the flow direction of the near infrared absorbing layer is easily obtained is preferable.

  In the present invention, the resin used for the near-infrared absorbing layer is not particularly limited as long as it can uniformly dissolve or disperse the near-infrared absorbing dye, but polyester, acrylic, polyamide, polyurethane, polyolefin, polycarbonate A series resin can be preferably used. Of these, acrylic resins having excellent heat resistance are preferred. Furthermore, the glass transition temperature of the resin is preferably equal to or higher than the guaranteed use temperature of the equipment to be used. However, an acrylic resin having a high glass transition temperature has poor flexibility, and the near-infrared absorbing layer is liable to be cracked by impact or bending. As will be described later, by including an ionic liquid in the near-infrared absorbing layer, flexibility can be imparted and improved.

  When the glass transition temperature is lower than the device operating temperature, the dyes dispersed in the resin react with each other, or the resin absorbs moisture in the outside air, and the deterioration of the dye and the binder resin increases. In the present invention, the glass transition temperature of the resin is not particularly limited as long as it is equal to or higher than the device use temperature, and particularly preferably 85 ° C. or higher and 160 ° C. or lower.

The glass transition temperature conforms to JIS K7121, and is performed using differential scanning calorimetry (DSC), and the glass transition temperature uses the extrapolated glass transition start temperature. The measurement procedure was as follows.
About 5 mg of sample was sealed in an aluminum pan for measurement and attached to a differential calorimeter (MAC Science DSC3100S). The temperature was raised from 30 ° C. to 200 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere, and 200 ° C. Take out the sample after it reaches, and immediately cool it down. The pan is again attached to the differential calorimeter, and the glass transition temperature (Tg: ° C.) is measured by increasing the temperature from 30 ° C. to 10 ° C./min.

  When the glass transition temperature of the resin used for the near-infrared absorbing layer is less than 85 ° C., the interaction between the dye and the resin, the interaction between the dyes, and the like occur, and the modification of the dye tends to occur. If the glass transition temperature exceeds 160 ° C., the resin must be dissolved in a solvent and heated to a sufficient temperature when applied on a transparent substrate. Poor property and further deterioration of the dye occurs. Moreover, when it dries at low temperature, drying time becomes long and productivity worsens, and productivity becomes bad. Further, there is a possibility that sufficient drying cannot be performed, so that the solvent remains in the coating film, the apparent glass transition temperature of the resin is lowered as described above, and similarly, the modification of the dye is likely to occur.

  The amount of the near-infrared absorbing pigment in the near-infrared absorbing layer is preferably 1% by mass or more and 10% by mass or less based on the resin. If the amount of the near-infrared absorbing dye in the resin is small, it is necessary to increase the coating amount of the near-infrared absorbing layer to achieve the target near-infrared absorbing ability. And / or it is necessary to make it for a long time, and the deterioration of the coloring matter or the poor flatness of the substrate tends to occur. Conversely, when the amount of near-infrared absorbing dye in the resin is large, the interaction between the dyes becomes strong, and even if the amount of residual solvent in the near-infrared absorbing layer is reduced, the dye is likely to change over time. Become.

  In the present invention, the near-infrared absorbing layer is formed by applying and drying a coating solution containing a near-infrared absorbing dye, a resin, and an organic solvent on a transparent substrate. At this time, it is important to contain a surfactant in the coating solution. By including the surfactant, the coating appearance of the near-infrared absorbing layer, in particular, dents due to minute bubbles and adhesion of foreign matter, etc., and repellency in the drying process are improved. Furthermore, the surfactant bleeds and localizes on the surface by coating and drying, so that when a surfactant having a low HLB is added, not only the durability is improved, but also slipperiness is imparted, and the near-infrared absorbing layer Alternatively, and / or without having surface irregularities on the opposite surface, the handleability is good and it is easy to wind up in a roll shape.

  As the surfactant, a known cationic, anionic, or nonionic surfactant can be suitably used, but a nonionic surfactant that does not have a polar group is preferred in view of problems such as deterioration with a near-infrared absorbing dye. A silicon-based or fluorine-based surfactant having excellent surface activity is preferable.

  Silicone surfactants include dimethyl silicon, amino silane, acrylic silane, vinyl benzyl silane, vinyl benzyl silyl amino silane, glycid silane, mercapto silane, dimethyl silane, polydimethyl siloxane, polyalkoxy siloxane, hydrodiene modified siloxane, vinyl modified siloxane, Vitroxy modified siloxane, amino modified siloxane, carboxyl modified siloxane, halogenated modified siloxane, epoxy modified siloxane, methacryloxy modified siloxane, mercapto modified siloxane, fluorine modified siloxane, alkyl group modified siloxane, phenyl modified siloxane, alkylene oxide modified siloxane, etc. .

  Fluorosurfactants include ethylene tetrafluoride, perfluoroalkyl ammonium salt, perfluoroalkyl sulfonic acid amide, sodium perfluoroalkyl sulfonate, perfluoroalkyl potassium salt, perfluoroalkyl carboxylate, perfluoroalkyl sulfone. Acid salts, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trimethyl ammonium salts, perfluoroalkyl amino sulfonates, perfluoroalkyl phosphate esters, perfluoroalkyl alkyl compounds, perfluoroalkyl alkyl betaines, perfluoroalkyl halides, etc. Is mentioned.

  The content of the surfactant is preferably 0.01% by mass or more and 2.00% by mass or less with respect to the resin constituting the near infrared absorption layer. When the surfactant content is low, the effect of improving the coating appearance and imparting slipperiness is insufficient. Conversely, when the surfactant content is high, the near-infrared absorbing layer tends to absorb moisture, resulting in deterioration of the pigment. May be promoted.

  In the present invention, the HLB of the surfactant is preferably 2 or more and 12 or less. The lower limit value of HLB is preferably 3, particularly preferably 4. On the other hand, the upper limit value of HLB is preferably 11, particularly preferably 10. When the HLB is low, the surface becomes water-repellent and the deterioration of the pigment due to moisture and heat resistance can be suppressed, and it is easy to impart slipperiness, but when it is too low, the leveling property is insufficient due to insufficient surface activity. Tends to be insufficient. On the other hand, when the HLB is high, not only the slipping property is insufficient, but also the near-infrared absorbing layer tends to absorb moisture, and the temporal stability of the dye tends to be poor.

  The HLB is a W.A. of Atlas Powder, Inc. of the United States. C. Griffin named Hydrophile Lyophile Balance and indexed the balance of hydrophilic groups and lipophilic groups contained in the surfactant molecules as characteristic values. The lower the value, the more hydrophilic the higher the hydrophilicity. Get higher.

  The localization of the surfactant on the surface of the near-infrared absorbing layer varies depending on the type of resin and the solvent, but it is most likely to occur when the HLB value is around 7 and the initial drying is more gradual. . The degree of localization is to compare the amount of surfactant near the surface of the near infrared absorbing layer measured using ESCA with the amount of surfactant in the near infrared absorbing layer measured by chemical analysis. Can be evaluated.

  In the present invention, it is important to contain an ionic liquid in the near-infrared absorbing layer. By containing the ionic liquid, not only the flexibility of the near-infrared absorbing layer is improved, but also the deterioration of the near-infrared absorbing dye, particularly the diimmonium salt compound, due to heat can be reduced. By containing a large amount of ions in the near-infrared absorbing layer, it can act as a plasticizer to impart flexibility, and further ion-exchange with the counter ion of the diimmonium salt compound for stabilization. When the counter ion of the diimmonium salt compound and the ionic liquid are the same, the low molecular weight counter ion contained in the other dye or resin prevents ion exchange with the counter ion of the diimmonium salt compound, thereby improving the heat resistance. .

  In the present invention, the ionic liquid is a liquid salt composed only of anions and cations.

The anionic species constituting the ionic liquid is not particularly limited. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ^{− and the} like can be mentioned. Among these, an anionic component containing a fluorine atom is easy to obtain an ionic compound having a low melting point, and the flexibility of the near-infrared absorbing layer is easily provided. Furthermore, when the counter ion of the diimmonium salt compound is bis (trifluoromethanesulfonyl) imidic acid, the effect of improving heat resistance can be obtained by using the same counter ion.

  Specific examples of the cationic species include imidazolium and pyridinium. Use of a material containing nitrogen-containing onium, sulfur-containing onium, or phosphorus-containing onium is preferable because it is possible to impart an antistatic effect to the near-infrared absorbing layer.

  A commercially available ionic liquid as described above may be used, but it can also be synthesized as follows. The method for synthesizing the ionic liquid is not particularly limited as long as the target ionic liquid is obtained. In general, the document “ionic liquids—the forefront and future of development” [CMC Publishing Co., Ltd.] A halide method, a hydroxide method, an acid ester method, a complex formation method, a neutralization method and the like as described in “Issuance” are used.

The content of the ionic compound is 0.1% by mass or more and 10.0% by mass or less in the near infrared absorption layer . If it is less than 0.1% by mass, the effect of improving heat resistance and imparting flexibility due to the inclusion of the ionic liquid is hardly exhibited. On the contrary, when it exceeds 10 mass%, it will precipitate on the surface of a near-infrared absorption layer, and adhesiveness with an adhesive will fall easily.

  In this invention, it is preferable to laminate | stack a near-infrared absorption layer by apply | coating and drying the coating liquid containing resin, a near-infrared absorption pigment | dye, and surfactant on a transparent base material. The coating solution needs to be diluted with an organic solvent because of coating properties.

  Examples of the organic solvent include (1) alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tridecyl alcohol, cyclohexyl alcohol, 2-methylcyclohexyl alcohol, and (2) ethylene glycol. , Glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, glycerin, (3) ethylene glycol monomethyl ether, ethylene glycol monoethylene ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Diethylene glycol butyl ether, ethylene glycol monomethyl Glycol ethers such as ether acetate, ethylene glycol monoethyl acetate, ethylene glycol monobutyl acetate, diethylene glycol monomethyl acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl acetate, (4) ethyl acetate, isopropylene acetate, n-butyl acetate, etc. Examples include esters, (5) ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, isophorone, diacetone alcohol, etc. These may be used alone or in combination of two or more. Can do.

  Preferably, ketones having excellent dye solubility are contained in an amount of 30% by mass to 80% by mass with respect to the total organic solvent used in the coating solution. Other organic solvents are preferably selected in consideration of leveling properties and drying properties. The boiling point of the organic solvent is preferably 60 ° C. or higher and 180 ° C. or lower. When the boiling point is low, the solid content concentration of the coating solution changes during coating, and the coating thickness is difficult to stabilize. On the other hand, when the boiling point is high, the amount of the organic solvent remaining in the coating film increases and the temporal stability becomes poor.

  Examples of the method for dissolving or dispersing the near-infrared absorbing dye and the resin in an organic solvent include stirring, dispersion and pulverization methods under heating. By heating, the solubility of the pigment and the resin can be improved, and a defect in the coating appearance due to undissolved substances or the like is prevented. Moreover, it becomes possible to form a layer having excellent transparency by dispersing and pulverizing the resin and the pigment in the coating liquid in a fine particle state of 0.3 μm or less. As the disperser and the pulverizer, known ones can be used. Specifically, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a colloid mill, an ultrasonic homogenizer, a homomixer, a pearl mill, a wet jet mill, a paint Examples include a shaker, a butterfly mixer, a planetary mixer, a Henschel mixer, and the like.

  When contamination or undissolved material of 1 μm or more is present in the coating solution, the appearance after coating becomes poor. Therefore, it is necessary to remove it with a filter or the like before coating. Various filters can be suitably used as the filter, but it is preferable to use a filter that removes 99% or more of a 1 μm size filter. When a coating liquid containing 1 μm or more of contamination or undissolved material is applied and dried, a dent or the like is generated around the coating liquid, which may be a defect of a size of 100 to 1000 μm.

  The solid content concentration of the resin and the pigment contained in the coating solution is preferably 10% by mass or more and 30% by mass. When the solid content concentration is low, it takes time to dry after coating, resulting in poor productivity and an increase in the amount of solvent remaining in the coating film, resulting in poor temporal stability. On the other hand, when the solid content concentration is high, the viscosity of the coating solution becomes high and the leveling property is insufficient, resulting in a poor coating appearance. The viscosity of the coating solution is preferably 10 cps or more and 300 cps or less from the viewpoint of coating appearance, and it is preferable to adjust the solid content concentration, the organic solvent, etc. so as to be in this range.

  In the present invention, as a method of laminating a near infrared absorption layer on a transparent substrate by a coating method, gravure coating method, kiss coating method, dip method, spray coating method, curtain coating method, air knife coating method, blade coating method, reverse Conventionally used methods such as a roll coating method, a bar coating method, and a lip coating method can be applied. Among these, a gravure coating method that can be applied uniformly, particularly a reverse gravure method is preferable. The diameter of the gravure is preferably 80 mm or less. When the diameter is large, the frequency of occurrence of ridges in the flow direction increases.

The coating amount of the near infrared absorbing layer after drying is not particularly limited, but the lower limit is preferably 1 g / m ² , more preferably 3 g / m ² , and the upper limit is preferably 50 g / m ² , more preferably 30 g / m. ² . When the coating amount after drying is small, the near-infrared absorbing power tends to be insufficient. Therefore, when the amount of the near-infrared absorbing dye in the resin is increased, the distance between the dyes is shortened, so that the interaction between the dyes is strengthened. As a result, the deterioration of the dye is likely to occur, and the temporal stability becomes poor. Conversely, when the coating amount after drying is large, the near-infrared absorbing ability is sufficient, but the transparency in the visible light region is lowered, and the brightness of the display is lowered. Therefore, if the amount of the near-infrared absorbing dye in the resin is reduced, the optical characteristics can be adjusted, but drying tends to be insufficient. As a result, the temporal stability of the dye becomes poor due to the residual solvent in the coating film. On the other hand, when the drying is sufficient, the flatness of the substrate becomes poor.

As a method for applying the coating liquid on the transparent substrate and drying, known hot air drying, an infrared heater, and the like can be mentioned. Hot air drying with a high drying speed is preferable.
In the initial constant rate drying stage after coating, drying is preferably performed at 20 ° C. or more and 80 ° C. or less using hot air of 2 m / sec or more and 30 m / sec. When initial drying is performed strongly (hot air temperature is high, hot air volume is large), not only the surfactant is not localized on the surface, it is difficult to improve durability and impart sliding properties, Minute defects of the coating such as fine coat removal, fine repellency, cracks and the like derived from bubbles are likely to occur. Conversely, if initial drying is weak (hot air temperature is low, hot air volume is small), the appearance will be good, but it will take time to dry and there will be problems in terms of cost as well as problems such as brushing. . When a surfactant is not added to the coating solution, the above minute defects are likely to occur, and the initial drying needs to be considerably weakened.

  In the reduction drying process, it is necessary to increase the temperature higher than the initial drying to reduce the solvent in the coating film, and the preferable temperature is 120 ° C. or higher and 180 ° C. or lower. Particularly preferably, the lower limit is 140 ° C and the upper limit is 170 ° C. When the temperature is low, the solvent in the coating film is difficult to decrease and becomes a residual solvent, resulting in insufficient stability of the dye over time. On the other hand, when the temperature is high, not only the flatness of the base material becomes poor due to heat wrinkles, but also the near-infrared absorbing dye is deteriorated by heat. The passing time is preferably 5 seconds or more and 180 seconds or less. If the time is short, the amount of solvent remaining in the coating film will increase, resulting in poor stability over time. Conversely, if the time is long, not only will the productivity be poor, but heat wrinkles will occur on the substrate. Therefore, the flatness becomes poor. The upper limit of the passage time is particularly preferably 30 seconds from the viewpoint of productivity and flatness.

  In the final stage of drying, it is preferable to set the hot air temperature to be equal to or lower than the glass transition temperature of the resin, and to set the actual temperature of the base material to be equal to or lower than the glass transition temperature of the resin in a flat state. When leaving the drying furnace at a high temperature, when the coated surface comes into contact with the roll surface, slippage is poor, and not only scratches but also curls may occur.

(Near-infrared absorbing film)
In the present invention, the near infrared absorbing film is a film having a low transmittance in the near infrared region of 800 to 1200 nm and a high transmittance in the visible light region of 400 nm to 800 nm. The transmittance in the near infrared region is preferably as low as possible, specifically 40% or less, more preferably 30% or less. When the transmittance is high, absorption of near infrared rays emitted from the plasma display is insufficient, and malfunction of electronic equipment using the near infrared remote controller cannot be prevented.
The transmittance can be adjusted depending on the kind of the near infrared absorbing dye and the amount of the near infrared absorbing dye per unit area.

  As the color tone of the near-infrared absorbing film, when expressed in the Lab color system, the a value is preferably -10.0 to +10.0, and the b value is preferably -10.0 to +10.0. If it is this range, even if it installs in the front surface of a plasma display, it becomes a natural color and is preferable.

  The method for adjusting the color tone can be achieved by the kind of the above-mentioned near-infrared absorbing dye, the abundance of the near-infrared absorbing dye per unit area, and further mixing with other dyes. In addition, when pasting with other members, such as an electromagnetic wave prevention film, an antireflection film, glass, using the adhesion layer colored on the front or back of the near-infrared absorption film mentioned below, it becomes a natural color as an optical filter. It is preferable to adjust the color tone.

  As a coating appearance of the near-infrared absorbing layer, a defect having a diameter of 300 μm or more, more preferably 100 μm, should not be present. The defect of 300 μm or more becomes like a bright spot when installed on the front surface of the plasma display, and the defect becomes noticeable. Defects of 100 μm or more and less than 300 μm may be emphasized due to the lens effect or the like by bonding such as adhesive processing, and should be eliminated as much as possible. Also, streaks, unevenness, etc. with a thin coating layer become prominent on the front surface of the display and become a problem.

  It is preferable that the near-infrared absorbing film does not change the transmittance of near-infrared rays and the transmittance of visible light even when left for a long period of time under high temperature and high humidity. When the temporal stability under high temperature and high humidity is poor, not only the color tone of the image on the display changes, but also the effect of the present invention for preventing malfunction of the electronic device using the near infrared remote controller may be lost.

  In order to improve the stability over time, it varies depending on the type of pigment and resin and additives, but the near-infrared absorbing layer can be controlled by controlling the type of organic solvent used in the coating solution, the thickness of the coating layer, the drying conditions, etc. It can be improved by reducing the amount of residual solvent in the resin or adjusting the content of the pigment in the resin. The amount of residual solvent in the near infrared absorbing layer is preferably as small as possible, but is preferably 3% by mass or less. If the amount is 3% by mass or less, there is substantially no difference in stability over time. However, in order to further reduce the amount of residual solvent, for example, if drying is performed under severe conditions, problems such as poor planarity of the filter occur, and productivity such as reduced pressure drying decreases.

  In the present invention, other functions may be imparted to the surface where the near-infrared absorbing layer is not provided. Specific examples include an antistatic layer, an easy adhesion layer, an easy slip layer, an antireflection layer, and an electromagnetic wave prevention layer. By providing the antireflection layer and the electromagnetic wave prevention layer, the number of members of the optical filter can be reduced, and not only can the cost be reduced, but also the light interference surface can be reduced and the image quality of the plasma display can be improved. When the near-infrared absorbing layer is formed, the antistatic layer can reduce the adhesion of dust in the post-process, and can reduce micro defects and improve the yield during manufacturing. The easy-adhesion layer can improve the adhesion when bonded to another member with an adhesive, and the easy-slip layer can improve the handling properties.

  As the antistatic agent used for the antistatic layer, known ones can be used, but when the near-infrared absorbing film is wound on a roll, the near-infrared absorbing layer comes into contact with Infrared absorbing dyes, especially diimmonium salt compounds, may deteriorate, so it is not preferable to use anionic or cationic surfactant types or quaternary ammonium salt cationic resins. It is necessary to contain molecules. The π-conjugated conductive polymer does not promote deterioration of near-infrared absorbing dyes, particularly diimmonium salts, and conversely, stability over time may be improved. Examples of the π-conjugated conductive polymer include aniline and / or a derivative thereof, pyrrole and / or a derivative thereof, isothianaphthene and / or a derivative thereof, acetylene and / or a derivative thereof, thiophene and / or a derivative thereof, and the like. . Of these, thiophene and / or its derivatives with less coloring are preferred.

  In the present invention, for the purpose of blocking harmful electromagnetic waves emitted from the display, a conductive layer may be provided on the same surface as the infrared absorbing layer or on the opposite surface directly or via an adhesive. Either a metal mesh or a conductive thin film may be used for the conductive layer. When a metal mesh is used, it is necessary to have a metal mesh conductive layer having an aperture ratio of 50% or more. If the aperture ratio of the metal mesh is low, the electromagnetic shielding property is good, but there is a problem that the light transmittance is lowered. For this reason, an aperture ratio of 50% or more is necessary to obtain a good light transmittance. Become. As the metal mesh used in the present invention, a metal foil having high electrical conductivity is subjected to etching treatment to form a mesh, a woven mesh using metal fibers, or metal on the surface of polymer fibers. You may use the fiber adhered using methods, such as plating. The metal used for the electromagnetic wave absorbing layer is not particularly limited as long as it has high electrical conductivity and good stability, but is not particularly limited, but from the viewpoint of workability, cost, etc., preferably copper, nickel, Tungsten etc. are good.

  When a conductive thin film is used, the transparent conductive layer may be any conductive film, but is preferably a metal oxide. Thereby, a higher visible light transmittance can be obtained. Further, in the present invention, when it is desired to improve the conductivity of the transparent conductive layer, it is preferably a repeating structure of three or more layers of metal oxide / metal / metal oxide. Conductivity can be obtained while maintaining a high visible light transmittance by multilayering the metal. Used in the present invention. The metal oxide may be any metal oxide as long as it has electrical conductivity and visible light transmittance. Examples include tin oxide, indium oxide, indium tin oxide, zinc oxide, titanium oxide, and bismuth oxide. The above is an example and is not particularly limited. The metal layer used in the present invention is preferably gold, silver or a compound containing them from the viewpoint of conductivity.

  Furthermore, when the conductive layer is multi-layered, for example, when the number of repeated layers is 3, the thickness of the silver layer is preferably 50 to 200 mm, more preferably 50 to 100 mm. When the film thickness is thicker than this, the light transmittance decreases, and when it is thin, the resistance value increases. Further, the thickness of the metal oxide layer is preferably 100 to 1000 mm, more preferably 100 to 500 mm. If it is thicker than this, it will be colored to change its color tone, and if it is thin, the resistance value will increase. In addition, when three or more layers are formed, for example, when five layers are formed such as metal oxide / silver / metal oxide / silver / metal oxide, the thickness of the central metal oxide is the other metal. It is preferable that it is thicker than the thickness of the oxide layer. By doing so, the light transmittance of the entire multilayer film is improved.

  The antireflection layer has a function of preventing surface reflection and preventing reflection of a fluorescent lamp or the like. The method of imparting the antireflection function can be arbitrarily selected without limitation. For example, a method of laminating layers having different refractive indexes on the surface of a base material and reducing the interference by using interference of reflected light at the interface of the layers And a method of providing irregularities on the surface. As a method for forming the antireflection film of this method, the following two methods can be broadly mentioned. One method is to form an antireflection film on the surface of the substrate by vapor deposition or sputtering, and the other method is to apply an antireflection coating solution to the surface of the substrate and dry it. This is a method for forming an antireflection film. As a general theory, it is said that the former is superior in terms of antireflection characteristics and the latter is superior in terms of economy, but either method may be used in the present invention.

(Optical filter)
In the present invention, the optical filter is installed on the front surface of the plasma display, cuts near infrared rays and electromagnetic waves generated from the display, and prevents reflection to improve display visibility, improves color reproducibility, etc. And further has a display protection function.

  An example of an optical filter is a structure in which an antireflection film, glass, an electromagnetic wave prevention film, and a near infrared absorption film are bonded with an adhesive. The adhesive has an ultraviolet absorbing ability, a color correction function, and a color reproducibility improving function. It is preferable to give. In addition, it is preferable to use a composite film having different functions on the same surface or the opposite surface of the film in terms of reducing the number of members, quantification, and the like. Furthermore, a direct attachment filter that is directly attached to a panel of a plasma display without using glass is also preferable for weight reduction and high image quality.

  In the present invention, the near-infrared absorbing film of the present invention can be suitably used when an optical filter is bonded directly to a plasma display panel without using glass. The image quality can be improved by directly attaching the optical filter, but the heat of the panel is easily transmitted and high heat resistance is required. In addition, measurement can be achieved by not using glass, but problems such as cracks are likely to occur due to external impacts, and high flexibility is required.

  Next, examples and comparative examples of the present invention will be shown. The characteristic value measurement method and effect evaluation method used in the present invention are as follows.

<Viscosity of coating solution>
The coating solution was adjusted to 20 ° C. and measured using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., BL) at a rotor rotational speed of 60 rpm.

<Transmissivity>
Using a spectrophotometer (Hitachi U-3500 type), in the wavelength range of 1100 to 200 nm, the near-infrared absorbing layer side was irradiated with light, and indoor air was measured as a reference for transmittance.

<Color tone>
Using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., ZE-2000), measurement was performed with a D65 light source and a viewing angle of 10 degrees so that the near infrared absorption layer side was irradiated with light.

<Heat and heat resistance>
The color tone after being allowed to stand for 500 hours in an atmosphere at a temperature of 60 ° C. and a humidity of 95% was measured, and the change amounts Δx and Δy of the color tone before and after treatment were obtained.

<Heat resistance>
The color tone after standing for 500 hours in an atmosphere at a temperature of 90 ° C. was measured, and the change amounts Δx and Δy of the color tone before and after the treatment were obtained.

<Flexibility>
The film was cut into a width of 10 mm, wound around a metal rod with the near infrared absorption layer on the outside, and the presence or absence of cracks in the near infrared absorption layer was confirmed. Twenty metal rods having a diameter of 1 to 20 mm and an interval of 1 mm were used, and the minimum diameter at which no cracks occurred was defined as an evaluation value of flexibility.

Example 1
1. Production of transparent substrate (1) Preparation of UV-absorber-containing masterbatch Dried UV-absorber (Cytech, CYASORB UV-3638; 2,2 '-(1,4-phenylene) bis (4H-3, 1-benzoxazinon-4-one)) 10 parts by mass, 90 parts by mass of polyethylene terephthalate (PET) resin (Toyobo Co., Ltd., ME553) containing no particles were mixed, and a master batch was prepared using a kneading extruder. . The extrusion temperature at this time was 285 ° C., and the extrusion time was 7 minutes.

(2) Preparation of coating solution for forming an easy-adhesion layer A coating solution for forming an easy-adhesion layer was prepared according to the following method. A reaction vessel was charged with 95 parts by weight of dimethyl terephthalate, 95 parts by weight of dimethyl isophthalate, 35 parts by weight of ethylene glycol, 145 parts by weight of neopentyl glycol, 0.1 part by weight of zinc acetate and 0.1 part by weight of antimony trioxide. The transesterification was carried out over 3 hours. Next, 6.0 parts by mass of 5-sodium sulfoisophthalic acid was added, and after esterification at 240 ° C. for 1 hour, a polycondensation reaction was performed to obtain a polyester resin. 6.7 parts by mass of a 30% by mass aqueous dispersion of the obtained polyester resin, 20% by mass aqueous solution of a self-crosslinking polyurethane resin containing an isocyanate group blocked with sodium bisulfite (Elastolone H 3) 40 parts by mass, elastron catalyst (Cat 64) 0.5 parts by mass, water 47.8 parts by mass and isopropyl alcohol 5 parts by mass, respectively, and an anionic surfactant with respect to the coating solution 1% by mass and 5% by mass of colloidal silica particles (manufactured by Nissan Chemical Industries, Snowtex OL) based on the solid content of the coating solution were added to obtain a coating solution.

(3) Film formation of base film 90 parts by mass of PET resin pellets (ME553, manufactured by Toyobo Co., Ltd.) having an intrinsic viscosity of 0.62 dl / g and not containing particles, and 10 parts by mass of the above-described UV absorber-containing masterbatch Were dried under reduced pressure at 135 ° C. for 6 hours (1 Torr) and then fed to an extruder. The resin temperature up to the extruder melt section, kneading section, polymer tube, gear pump, and filter was 280 ° C., and the polymer tube thereafter was 275 ° C., and the sheet was extruded from the die in the form of a sheet. These polymers were each filtered using a stainless steel filter medium (nominal filtration accuracy: 95% of particles having a size of 10 μm or more). Further, the resin temperature of the flat die was set to 275 ° C. The extruded resin was wound around a casting drum (roll diameter: 400φ, Ra: 0.1 μm or less) having a surface temperature of 30 ° C. using an electrostatic application casting method, and solidified by cooling to produce an unstretched film. The discharge rate at this time was 48 kg / hr, and the obtained unstretched sheet had a width of 300 mm and a thickness of 1400 μm. Next, the cast film is heated to 100 ° C. using a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction (running direction) with a roll group having a difference in peripheral speed, and a uniaxially oriented film Got. With respect to all rolls used in the production of the film, the surface roughness of the roll was controlled to be 0.1 μm or less by Ra, and roll cleaners were installed at the preheating inlet and the cooling roll in the longitudinal stretching step. The roll diameter in the longitudinal stretching step was 150 mm, and the film was brought into close contact with the roll using a suction roll, electrostatic contact, and part nip contact apparatus. Thereafter, the coating solution for forming an easy-adhesion layer was finely filtered with a felt type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) of 25 μm, applied to both sides by a reverse roll method, and dried. After coating, the film edge is subsequently held with a clip and guided to a hot air zone heated to 130 ° C., dried, stretched 4.0 times in the width direction, and heat treated at 230 ° C. for 5 seconds. In the process, 3% relaxation treatment was performed in the width direction to obtain a base film (B). The film thickness was 100 μm, and the coating amount of the easy adhesion layer at this time was 0.01 g / m ² . The transmittance of the obtained film at a wavelength of 380 nm was 4% and had excellent ultraviolet absorptivity. Further, the total light transmittance was 91% and the haze was 0.6%, which was excellent in transparency.

2. Lamination of near-infrared absorbing layer Apply the following coating solution A (viscosity: 23 cps) on the above intermediate coating layer in reverse using a diagonal gravure with a diameter of 60 cm so that the transmittance at 950 nm is 4.3%. Near-infrared absorbing filter, dried for 20 seconds with hot air of 5 m / second at 40 ° C., 20 seconds with hot air of 20 m / second at 150 ° C. and further with hot air of 20 m / second at 90 ° C. for 10 seconds. It was created.
(Coating liquid A for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Next, the coating solution A was prepared by removing undissolved substances with a filter having a nominal filtration accuracy of 1 μm.
・ Toluene 22.193 mass%
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
-Diimonium salt compound (Dye A) 0.937% by mass
(Nippon Carlit, CIR1085, counter ion: bis (trifluoromethanesulfonyl) imidic acid)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)
・ Ionic liquid C 0.890 mass%
(N-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Example 2
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution B was used.
(Coating solution B for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Next, the coating solution B was prepared by removing undissolved substances with a filter having a nominal filtration accuracy of 1 μm.
・ Toluene 22.998% by mass
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
-Diimonium salt compound (Dye A) 0.937% by mass
(Nippon Carlit, CIR1085, counter ion: bis (trifluoromethanesulfonyl) imidic acid)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)
・ Ionic liquid C 0.085 mass%
(N-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Example 3
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution C was used.
(Coating liquid C for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Subsequently, the undissolved material was removed with a filter having a nominal filtration accuracy of 1 μm to prepare coating solution C.
・ Toluene 21.411% by mass
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
-Diimonium salt compound (Dye A) 0.937% by mass
(Nippon Carlit, CIR1085, counter ion: bis (trifluoromethanesulfonyl) imidic acid)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)
・ Ionic liquid C 1.671 mass%
(N-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Comparative Example 1
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution D was used.
(Coating liquid D for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Subsequently, the undissolved material was removed with a filter having a nominal filtration accuracy of 1 μm to prepare the coating solution D.
・ Toluene 23.083% by mass
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
-Diimonium salt compound (Dye A) 0.937% by mass
(Nippon Carlit, CIR1085, counter ion: bis (trifluoromethanesulfonyl) imidic acid)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region was obtained. Although the transmittance | permeability in visible region was a little lower than Examples 1-3 which added the ionic liquid, the film was obtained. Heat resistance and flexibility were poor.

Example 4
In Example 1, the near-infrared absorption film was obtained like Example 1 except having changed the kind of ionic liquid into the following ionic liquid D. FIG.
Ionic liquid D: n-butyl-3-methylpyridinium tetrafluoroborate

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 1 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Example 5
In Example 1, the near-infrared absorption film was obtained like Example 1 except having changed the kind of ionic liquid into the following ionic liquid E. FIG.
Ionic liquid E: N, N, N-trimethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region was obtained. Although heat resistance was inferior to Example 1, it was better than Comparative Example 1. Also, the flexibility was good.

Example 6
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution E was used.
(Coating liquid E for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Next, the coating solution E was prepared by removing undissolved substances with a filter having a nominal filtration accuracy of 1 μm.
・ Toluene 22.193 mass%
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
-Diimonium salt compound (Dye B) 0.937% by mass
(Nippon Carlit, CIR1081, counter ion: antimony hexafluoride)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)
・ Ionic liquid C 0.890 mass%
(N-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Comparative Example 2
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that the following coating solution F was used.
(Coating solution F for near-infrared absorbing layer)
The materials of the coating solution were mixed at the following mass ratio and stirred for 30 minutes or more. Next, the coating solution E was prepared by removing undissolved substances with a filter having a nominal filtration accuracy of 1 μm.
・ Toluene 23.083% by mass
・ Methyl ethyl ketone 23.083 mass%
-Acrylic resin 52.762 mass%
(Soken Chemicals, GS-1030, solid content: 30% by mass, Tg: 115 ° C.)
・ Diimonium dye 0.937 mass%
(Nippon Carlit, CIR1081, counter ion: antimony hexafluoride)
・ Cyanine dye 0.076 mass%
(Asahi Denka Kogyo, TZ-123)
・ Silicone surfactant 0.059% by mass
(Dow Corning, Paintad 57, HLB: 6.7)

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

Example 7
A near-infrared absorbing film was obtained in the same manner as in Example 1 except that a reflective film (manufactured by NOF Corporation, Realak 7700S) was used as the transparent substrate, and a near-infrared absorbing layer was laminated on the surface opposite to the antireflection layer. It was.

  Table 1 shows the types of near-infrared absorbing dyes (diimmonium salt compounds) in the near-infrared absorbing layer and the types and contents of ionic liquids. In addition, Table 2 shows the physical properties of the obtained near-infrared absorbing film. A film having strong absorption in the near infrared region and high transmittance in the visible light region was obtained. Moreover, heat resistance and flexibility were also good.

  When the near-infrared absorbing film of the present invention is installed on the front surface of the plasma display as a near-infrared absorbing filter, like the conventional near-infrared absorbing filter, it absorbs unnecessary near-infrared rays emitted from the display and malfunctions of precision equipment. In addition to being able to prevent color change due to heat, it can greatly reduce the change in color tone due to heat, contributing to higher image quality of plasma displays and increasing the degree of freedom in designing optical filters. It is important to contribute to the industry.

Claims (5)

A near-infrared absorbing film provided with a near-infrared absorbing layer comprising a composition mainly composed of a near-infrared absorbing dye and a resin on a transparent substrate, wherein an ionic liquid is added to the composition in an amount of 0.1 A near-infrared absorbing film, which is contained by mass% to 10.0 mass% .   The near-infrared absorbing film according to claim 1, wherein the near-infrared absorbing dye contains a diimmonium salt compound.   The near-infrared absorbing film according to claim 1 or 2, wherein the near-infrared absorbing dye is a diimmonium salt compound having bis (trifluoromethanesulfonyl) imidic acid as a counter ion. Near infrared absorbing film according to any one of claims 1 to 3, wherein the ionic liquid characterized by comprising bis (trifluoromethanesulfonyl) imide acid as anion. Near infrared absorbing film according to any one of claims 1 to 4, the resin constituting the near-infrared absorption layer, characterized in that an acrylic resin.